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Q1. Define conditional probability

Solution

Conditional Probability: If A and B are two events of sample space S associated with a random experiment, then occurrence of A provided B has already occurred is called conditional probability. It is denoted by P(A | B).  
Q2. Define posteriori probability

Solution

Posteriori Probability: If E1, E2, ..., En are the partitions of a sample space S, then the probability P(Ei) is called the priori probability of the hypothesis Ei  and the conditional probability P(Ei |A) is called a posteriori probability of the hypothesis Ei.  
Q3. Define Bernoulli trials.

Solution

Bernoulli Trials: Trials of a random experiment are called Bernoulli trials, if they satisfy the following conditions: (i) There should be a finite number of trials. (ii) The trials should be independent. (iii) Each trial has exactly two outcomes: success or failure. (iv) The probability of success remains the same in each trial
Q4. Differentiate sin (2x + 3) w. r. t. x from first principle.

Solution

Not in current syllabus
Q5. A die is thrown twice and the sum of the numbers appearing is observed to be 9.What is the conditional probability that 4 has appeared atleast once?

Solution

Let A be the event that sum appears to be 9={(3,6),(4,5),(5,4),(6,3)}  B be the event of getting 4 atleast once={(1,4),(2,4),(3,4),(4,1),(4,2),(4,3),(4,4),(4,5),(4,6),(5,4),(6,4)} AintersectionB will be {(4,5),(5,4)} P(B/A)=fraction numerator P left parenthesis A intersection B right parenthesis over denominator P left parenthesis A right parenthesis end fraction equals fraction numerator n left parenthesis A intersection B right parenthesis over denominator n left parenthesis A right parenthesis end fraction equals 2 over 4 equals 1 half
Q6. Define random variable.  

Solution

Random Variable: If S is the sample space associated with a random experiment. Then a real valued function which assign to each element of S, a unique real number is called a random variable.  
Q7. Consider the Experiment: Throw one die over and over until you get a six; X = the number of throws.What values can X take?

Solution

 If you throw a six on the first throw, X = 1. If you first throw one on the second, X = 2, and so on. Thus, the possible values of X are 1, 2, 3, ....
Q8. A bag contains 2 red and 3 black balls . One ball is drawn and put back into the bag.This is done three times and everytime a red ball is drawn, it is counted as a success.Let 'X' denote the number of successes.is 'X' a random variable. Justify your answer

Solution

An experiment is called random experiment if it satisfies the following two conditions: (i) It has more than one possible outcome. (ii) It is not possible to predict the outcome in advance. Here X has two possible outcomes, a success and a failure. It is also not possible to predict the outcome when a ball is drawn, in advance.So X is a random variable.
Q9. Define continuous and discrete random variable. 

Solution

(1)Continuous Random Variable: If a random variable X assumes all possible values in a given interval, then it is called continuous random variable.   (2) Discrete Random Variable: If a random variable X assumes only a finite or countable infinite set of values, then it is called discrete random variable.    
Q10. What are independent events? 

Solution

Independent Events: Two or more events are independent events, such that the probability of occurrence of one event is not affected by occurrence by other.


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